If you don’t see the file or document you’re looking for when you browse or search your Google Drive, it’s possible that you’ve moved it to Trash. Here’s how to find and recover something that you own from the trash:

If you’re missing content within a specific document, you can check its revision history (File > See revision history) to see if you or a collaborator deleted something from it. If you find the version that contains the content you were missing, click Restore this revision.

Files are orphaned due to situations related to sharing and permissions. For example:

User A creates folder X in his Drive.

User A shares folder X with user B.

User B creates item Y inside folder X.

User A trashes folder X, and empties his trash.

At this point, item Y becomes orphaned. It was never created inside of user B's My Drive, and its parent folder (folder X) is now gone. Note that item Y is not deleted along with with folder X because user A can't delete user B's file.